#include "SHA512.h"
#include <string.h>

static const unsigned long long _K[80] = {
	0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f, 0xe9b5dba58189dbbc,
	0x3956c25bf348b538, 0x59f111f1b605d019, 0x923f82a4af194f9b, 0xab1c5ed5da6d8118,
	0xd807aa98a3030242, 0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
	0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235, 0xc19bf174cf692694,
	0xe49b69c19ef14ad2, 0xefbe4786384f25e3, 0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65,
	0x2de92c6f592b0275, 0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
	0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f, 0xbf597fc7beef0ee4,
	0xc6e00bf33da88fc2, 0xd5a79147930aa725, 0x06ca6351e003826f, 0x142929670a0e6e70,
	0x27b70a8546d22ffc, 0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
	0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6, 0x92722c851482353b,
	0xa2bfe8a14cf10364, 0xa81a664bbc423001, 0xc24b8b70d0f89791, 0xc76c51a30654be30,
	0xd192e819d6ef5218, 0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
	0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99, 0x34b0bcb5e19b48a8,
	0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb, 0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3,
	0x748f82ee5defb2fc, 0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
	0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915, 0xc67178f2e372532b,
	0xca273eceea26619c, 0xd186b8c721c0c207, 0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178,
	0x06f067aa72176fba, 0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
	0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc, 0x431d67c49c100d4c,
	0x4cc5d4becb3e42b6, 0x597f299cfc657e2a, 0x5fcb6fab3ad6faec, 0x6c44198c4a475817
};

void Transform(StateSHA512*);
unsigned long long Choice(unsigned long long, unsigned long long, unsigned long long);
unsigned long long Majority(unsigned long long, unsigned long long, unsigned long long);
unsigned long long RotateRight(unsigned long long, int);
unsigned long long Func0(unsigned long long);
unsigned long long Func1(unsigned long long);
unsigned long long Func2(unsigned long long);
unsigned long long Func3(unsigned long long);

int SHA512_Init(StateSHA512* state)
{
	memset(state, 0, sizeof(StateSHA512));
	state->Digest[0] = 0x6a09e667f3bcc908;
	state->Digest[1] = 0xbb67ae8584caa73b;
	state->Digest[2] = 0x3c6ef372fe94f82b;
	state->Digest[3] = 0xa54ff53a5f1d36f1;
	state->Digest[4] = 0x510e527fade682d1;
	state->Digest[5] = 0x9b05688c2b3e6c1f;
	state->Digest[6] = 0x1f83d9abfb41bd6b;
	state->Digest[7] = 0x5be0cd19137e2179;
	return 0;
}

int SHA512_Update(StateSHA512* state, const char* str, int len)
{
	for (; len != 0; len--)
	{
		state->Buffer[state->Index++] = *str++;
		state->Bits[0] += 8;
		if (state->Bits[0] == 0)
		{
			state->Bits[1]++;
		}
		if (state->Index == 128)
		{
			Transform(state);
			state->Index = 0;
		}
	}
	return 0;
}

int SHA512_Final(StateSHA512* state, unsigned char out[64])
{
	static const unsigned char pad[128] = {
		0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
	};
	unsigned long long bits[2];
	int i, j;
	memcpy(bits, state->Bits, 16);
	SHA512_Update(state, pad, (state->Index < 122) ? (122 - state->Index) : (240 - state->Index));
	state->Buffer[112] = (bits[1] >> 56) & 0xFF;
	state->Buffer[113] = (bits[1] >> 48) & 0xFF;
	state->Buffer[114] = (bits[1] >> 40) & 0xFF;
	state->Buffer[115] = (bits[1] >> 32) & 0xFF;
	state->Buffer[116] = (bits[1] >> 24) & 0xFF;
	state->Buffer[117] = (bits[1] >> 16) & 0xFF;
	state->Buffer[118] = (bits[1] >> 8) & 0xFF;
	state->Buffer[119] = (bits[1]) & 0xFF;
	state->Buffer[120] = (bits[0] >> 56) & 0xFF;
	state->Buffer[121] = (bits[0] >> 48) & 0xFF;
	state->Buffer[122] = (bits[0] >> 40) & 0xFF;
	state->Buffer[123] = (bits[0] >> 32) & 0xFF;
	state->Buffer[124] = (bits[0] >> 24) & 0xFF;
	state->Buffer[125] = (bits[0] >> 16) & 0xFF;
	state->Buffer[126] = (bits[0] >> 8) & 0xFF;
	state->Buffer[127] = (bits[0]) & 0xFF;
	Transform(state);
	for (i = 0, j = 0; i < 64; i += 8, j++) // copy the digest into the output array (BigEndian)
	{
		out[i] = (unsigned char)((state->Digest[j] >> 56) & 0xFF);
		out[i + 1] = (unsigned char)((state->Digest[j] >> 48) & 0xFF);
		out[i + 2] = (unsigned char)((state->Digest[j] >> 40) & 0xFF);
		out[i + 3] = (unsigned char)((state->Digest[j] >> 32) & 0xFF);
		out[i + 4] = (unsigned char)((state->Digest[j] >> 24) & 0xFF);
		out[i + 5] = (unsigned char)((state->Digest[j] >> 16) & 0xFF);
		out[i + 6] = (unsigned char)((state->Digest[j] >> 8) & 0xFF);
		out[i + 7] = (unsigned char)((state->Digest[j]) & 0xFF);
	}
	return 0;
}

void Transform(StateSHA512* state)
{
	int i, j;
	unsigned long long W[80], a, b, c, d, e, f, g, h, temp0, temp1;
	memset(W, 0, sizeof(W));
	a = state->Digest[0];
	b = state->Digest[1];
	c = state->Digest[2];
	d = state->Digest[3];
	e = state->Digest[4];
	f = state->Digest[5];
	g = state->Digest[6];
	h = state->Digest[7];
	for (i = 0, j = 0; i < 16; i++)
	{
		W[i] |= RotateRight(state->Buffer[j++], 8);
		W[i] |= RotateRight(state->Buffer[j++], 16);
		W[i] |= RotateRight(state->Buffer[j++], 24);
		W[i] |= RotateRight(state->Buffer[j++], 32);
		W[i] |= RotateRight(state->Buffer[j++], 40);
		W[i] |= RotateRight(state->Buffer[j++], 48);
		W[i] |= RotateRight(state->Buffer[j++], 56);
		W[i] |= RotateRight(state->Buffer[j++], 64);
	}
	for (i = 16; i < 80; i++)
	{
		W[i] = Func3(W[i - 2]) + Func2(W[i - 15]) + W[i - 7] + W[i - 16];
	}
	for (i = 0; i < 80; i++)
	{
		temp0 = h + Func1(e) + Choice(e, f, g) + _K[i] + W[i];
		temp1 = Func0(a) + Majority(a, b, c);
		h = g;
		g = f;
		f = e;
		e = d + temp0;
		d = c;
		c = b;
		b = a;
		a = temp0 + temp1;
	}
	state->Digest[0] += a;
	state->Digest[1] += b;
	state->Digest[2] += c;
	state->Digest[3] += d;
	state->Digest[4] += e;
	state->Digest[5] += f;
	state->Digest[6] += g;
	state->Digest[7] += h;
}

unsigned long long Choice(unsigned long long a, unsigned long long b, unsigned long long c)
{
	return (a & b) ^ (~a & c);
}

unsigned long long Majority(unsigned long long a, unsigned long long b, unsigned long long c)
{
	return (a & b) ^ (a & c) ^ (b & c);
}

unsigned long long RotateRight(unsigned long long x, int bits)
{
	return (unsigned long long)((x >> bits) | (x << (64 - bits)));
}

unsigned long long Func0(unsigned long long x)
{
	return RotateRight(x, 28) ^ RotateRight(x, 34) ^ RotateRight(x, 39);
}

unsigned long long Func1(unsigned long long x)
{
	return RotateRight(x, 14) ^ RotateRight(x, 18) ^ RotateRight(x, 41);
}

unsigned long long Func2(unsigned long long x)
{
	return RotateRight(x, 1) ^ RotateRight(x, 8) ^ (x >> 7);
}

unsigned long long Func3(unsigned long long x)
{
	return RotateRight(x, 19) ^ RotateRight(x, 61) ^ (x >> 6);
}
